The present invention relates generally to molding and injection molding equipment and processes and, in particular, to a multi-shot molding method and assembly.
Molding and injection molding equipment are well known and typically include a mold having a mold cavity for receiving molten liquid therein for forming a finished molded part, such as automobile door interiors or the like. Multi-shot molding is also well known and typically includes the steps of injecting a first pressurized molten mold material into a mold cavity, retracting a portion of the mold (such as a large core, a small core, a blade, or a lifter) into the core or the cavity, and injecting at least a second pressurized molten mold material into the mold cavity to form a finished part formed of the first and second mold materials. Injection molding equipment typically utilize retractable, often tapered, pins for providing a means for attaching the first and second mold materials. The pin extends through the first mold material and is retracted, along with the retracting portion, prior to the second mold material being injected to form a connection, such as a welded connection, between the mold materials. The pin fully penetrates through the first material and contacts a surface of the core portion adjacent the mold cavity. Eventually, a witness mark is disadvantageously formed on the surface of the core portion that, in turn, becomes a blemish on a surface of the finished molded part.
It would be desirable, therefore, to provide an assembly and method for forming multi-shot molded parts that does not produce a witness mark on a surface of the finished molded product and that ensures proper attachment of the multiple shot components formed in the multi-shot molding process.